The present invention relates to a system and method for controlling the movement of one or more jet engine thrust reverser components. More particularly, the present invention relates to a system and method for controlling the movement of one or more jet engine thrust reverser components during a stowage operation of the thrust reversers.
When jet-powered aircraft land, the landing gear brakes and imposed aerodynamic drag loads (e.g., flaps, spoilers, etc.) of the aircraft may not be sufficient to slow the aircraft down in the required amount of distance. Thus, jet engines on most aircraft include thrust reversers to enhance the stopping power of the aircraft. When deployed, thrust reversers redirect the rearward thrust of the jet engine to a forward direction, thus decelerating the aircraft. Because the jet thrust is directed forward, the aircraft will slow down upon landing.
Various thrust reverser designs exist in the art, and the particular design utilized depends, at least in part, on the engine manufacturer, the engine configuration, and the propulsion technology being used. Thrust reverser designs used most prominently with turbofan jet engines fall into three general categories: (1) cascade-type thrust reversers; (2) target-type thrust reversers; and (3) pivot door thrust reversers. As will be discussed more fully below, each of these designs employs a different type of xe2x80x9cmoveable thrust reverser component,xe2x80x9d as that term is defined herein below.
Cascade-type thrust reversers are normally used on high-bypass ratio jet engines. This type of thrust reverser is located at the engine""s midsection and, when deployed, exposes and redirects air flow through a plurality of cascade vanes positioned on the outside of the engine. The moveable thrust reverser component in this design may include several translating sleeves or cowls (xe2x80x9ctranscowlsxe2x80x9d) that are deployed to expose the cascade vanes. Target-type reversers, also referred to as clamshell reversers, are typically used with low-bypass ratio jet engines. Target-type thrust reversers use two doors as the moveable thrust reverser component to block the entire jet thrust coming from the rear of the engine. These doors are mounted on the aft portion of the engine and form the rear part of the engine nacelle. Pivot door thrust reversers may utilize four doors on the engine nacelle as the moveable thrust reverser component. In the deployed position, these doors extend outwardly from the nacelle to redirect the jet thrust.
The primary use of thrust reversers is, as noted above, to enhance the stopping power of the aircraft, thereby shortening the stopping distance during landing. Hence, thrust reversers are primarily deployed during the landing process. More specifically, once the aircraft has touched down, the thrust reversers are deployed to assist in slowing the aircraft. Thereafter, when the thrust reversers are no longer needed, they are returned to their original, or stowed position. In the stowed position, one or more stow seals prevent air flow from flowing through the transcowls or doors, depending on the thrust reverser design. Moreover, stow locks are engaged to prevent unintended deployment of the thrust reversers.
When the thrust reversers are moved to the stowed position, the transcowls or doors must be held firmly against the stow seals while the stow locks are engaged. One problem associated with this operation is that structural damage may occur if the transcowls or doors are driven into the stow seals with too much force. Another problem occurs if power to move the transcowls or doors is removed too soon after the transcowls or doors contact the stow seals. In this case, the elasticity of the seals may push the transcowls or doors away from the seals before the stow locks are engaged. This latter problem may result in either a failure of the stow locks to engage or a limit cycle condition in which the thrust reverser system continuously cycles between hitting the seals and bouncing back off of them.
Hence, there is a need for a system for controlling the stowage of one or more jet engine thrust reversers that improves upon one or more of the drawbacks identified above. Namely, a system for controlling jet engine thrust reverser stowage that avoids structural damage by preventing the thrust reverser transcowls or doors from being driven into the stow seals with too much force, and/or that prevents the thrust reverser system from cycling between a stowed and a rebounded position, and/or that ensures the engagement of the stow locks.
The present invention provides a system and method for controlling the stowage of jet engine thrust reversers that avoids structural damage, and/or prevents a limit cycle condition, and/or ensures engagement of the stow locks.
In one aspect of the present invention, and by way of example only, a system for controlling one or more jet engine thrust reversers includes an electric motor, one or more moveable thrust reverser components, a position sensor, a controller circuit, and a timer circuit. The motor is coupled to the one or more moveable thrust reverser components for moving the one or more moveable thrust reverser components between a deployed position and a stowed position. The position sensor is operable to provide a position signal at least when the one or more moveable thrust reverser components attain a predetermined position relative to the stowed position. The controller is operably coupled to the motor and responsive to the position signal to rotate at a variable speed. The timer circuit has an output coupled to the controller circuit and is responsive to the position signal to cause the controller circuit to remove power to the motor a predetermined time period after the one or more moveable thrust reverser components attain the predetermined position.
In another aspect of the invention, a system for controlling one or more jet engine thrust reversers includes reverser moving means, position sensing means, controller means, and timer means. The moving means is for moving one or more thrust reverser moveable components to at least a stowed position. The position sensing means is for sensing at least when the one or more thrust reverser moveable components attain a predetermined position relative to the stowed position. The controller means is for causing the reverser moving means to move at a variable speed in response to the position sensing means sensing that the predetermined position is attained. The timer means causes the controller means to remove power supplied to the moving means a predetermined time period after the one or more moveable thrust reverser components attain the predetermined position.
In yet a further aspect of the present invention, a method of controlling one or more jet engine thrust reversers includes causing movement of one or more thrust reverser moveable components toward at least a stowed position. At least when the one or more thrust reverser moveable components attain a predetermined position relative to the stowed position is sensed. The speed of movement of the one or more thrust reverser moveable components is varied in response to the one or more thrust reverser moveable components attaining the predetermined position. The movement of the one or more thrust reverser moveable components is disabled a predetermined time period after sensing that the one or more moveable thrust reverser components have attained the predetermined position.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.